1. Field of the Invention
The present invention relates generally to aerodynamic devices for use with vehicles, such as trucks and semi-trailers, and in particular relates to an aerodynamic wind drag reduction device or airfoil for attachment to the rear of a truck or trailer by means of a collapsible frame.
2. Description of the Prior Art
The shape of conventional trucks and semi-trailers is dictated by a need to provide a large cargo volume within maximum allowable dimensions, and generally results in vehicles which sacrifice aerodynamic efficiency to obtain maximum cargo volume. Various devices have been proposed to increase the aerodynamic efficiency for trucks and trailers, including aerodynamic airfoils attached to the roof of trucks for pulling trailers, as well as devices for attachment to the rear of trailers to provide a streamlined shape in order to reduce the effects of the low pressure region created at the rear of the trailer.
Common problems addressed by prior art aerodynamic devices for attachment to the rear of trailers include accommodating the need for proper access to the rear of the trailer to permit loading and unloading of cargo. Accordingly, many prior art devices provide various mechanisms for providing folding frames to define the contour of the airfoil, or for providing an inflatable airfoil which collapses when the vehicle is not in motion. A further problem associated with such devices includes providing a convenient mechanism for extending and retracting the airfoil and which will not unduly alter the structure of the trailer or require extensive modifications.
Accordingly, there is a continuing need for an airfoil for use with a truck or semi-trailer to reduce aerodynamic drag and which requires a minimum number of moving parts resulting in easier and faster deployment and in a reduced cost. There is a further need for such a device in which the airfoil may be incorporated into vehicles having either pivoted doors or roll up door closures.